In general, when preparing ready meals of the type considered it is necessary to satisfy a dual requirement, that is, on the one hand to ensure that the product remains non-toxic for longer than the declared long-life period and, on the other, to keep the physical and organoleptic qualities of the product (ready meal) as close as possible to those of the same dish fleshly prepared.
To this end, the prior art provides numerous processes which may be divided into two groups, each based on a different method of administering the heat for carrying out the stabilisation/sterilisation and cooking operations, namely:
1) processes which use electromagnetic energy (in particular microwaves or infrared radiation) to provide the heat, and PA1 2) processes which use steam and/or a cooking liquid (for example water, oil and the like).
One technique of the second group is taught, for example, by U.S. Pat. No. 4 882 191 which describes a process for the continuous preparation of ready meals based on pasta. This process provides for a sequence of operations (sterilisation by steam, cooking in water, straining, cooling) carried out in a sterile environment on pasta measured into open containers which are then sealed, also in a sterile environment, following the possible addition of a condiment.
In other processes of the second group, aimed in particular at the preparation of ready meals based on meat, fish, vegetables and the like, where no cooking liquid is used, there is obviously no straining step; in yet other processes the cooking liquid is also used to stabilise and/or sterilise the product and the container.
In order to carry out such processes, the prior art provides an equally numerous selection of equipment, the structural and operating characteristics whereof are so specialised that, in general, not only is it not possible to use the same plant for two different processes but it is equally impossible to carry out this same process on two different products, even if they belong to a same product family. This rule is especially true when the selected process is required to be continuous.
It is known that, in order to obtain optimum products both from an organoleptic point of view and from that of the product-life, it is necessary to use different processing temperatures and times as well as different pressures, volumes of liquid and the like, not only for products of a different nature (such as, for example, pasta, vegetables and meat) but also for similar products, such as pasta products which differ in thickness, dimensions, weight, consistency and shape.
It is therefore understandable that the rigid restrictions imposed by the use of prior art apparatus constitute a serious problem for all companies involved in the production of ready meals spread across a broad range of basic products. A few attempts have been made to adapt existing plants to a variety of ready meals but have led to considerable complications in the structure and operation of such plants and have produced products which are not entirely satisfactory from an organoleptic point of view.
The problem forming the basis of this invention is that of designing and providing a plant for the heat-stabilisation and/or sterilisation and cooking of food products in general which has structural and operating characteristics such as to enable it to be used to advantage to produce so-called ready meals based on a variety of products, differing by nature, weight, consistency, dimensions and shape, while at the same time enabling all operating steps to be controlled precisely and automatically.
This problem is solved according to the invention by a plant of the type considered, the characteristics whereof are indicated in Claim 1 which follows.
The advantages and characteristics of this invention will become more apparent from the detailed description of one embodiment thereof, given by way of example with reference to the appended drawings, provided purely by way of non-limitative example.